He said on Friday that Catholics were ready "to help in a constructive dialogue necessary to avoid trauma."

But the pontiff added that it was "obvious that the church is always on the side of freedom of conscience, freedom of religion" and that in Cuba, "ordinary Catholics contribute to finding the path forward."

However, nobody expects a clash between the pontiff and the Cuban government, even as it continued a government crackdown on its opponents.

At least 70 dissidents have been arrested by Cuban authorities in an effort to stop a demonstration during Benedict XVI's visit, opposition sources said.

At least 15 of those detained were members of the Ladies in White, a prominent group of wives and family members of jailed political opponents, according to the dissidents.

The Cuban Human Rights and National Reconciliation Commission, a dissident group, said the arrests took place in the eastern city of Santiago de Cuba, where the pope was due to arrive Monday.

Benedict XVI underscored his commitment to "absolute continuity" of the course laid out by the historic journey of Pope John Paul II on the island in January 1998.

"The Holy See knows the ideological positions of the Cuban government" and the government "is aware of the views of the Church," said Archbishop Dionisio Garcia of Santiago de Cuba.

He said he did not believe the comments made by the pope would have repercussions on the visit.

"The pope said something that is obvious," the archbishop said. "Marxism, as it was designed, should be overstepped and revised, and not only in Cuba."

Benedict XVI has no plans to meet with members of the Cuban opposition. The pope "knows the Cuban reality" and the fact "he meets with the opponents or not does not mean he is unaware" of their situation, Garcia said Saturday.

However, the Vatican said the pope would be "available" for a possible meeting with the father of the Cuban Revolution, Fidel Castro, who left power due to ill health in 2006.

Cuba's Roman Catholics account for about 10 per cent of the population of 11 million, after 40 years of official atheism ended in the 1990s. Evangelical Protestants are making inroads here as elsewhere, but most Cubans identify most with AfroCuban belief systems, such as Santeria and Palo Monte.

Workers, racing against the clock, have pieced together the huge altar where Pope Benedict is to say mass later this week in sprawling Revolution Square. It has been the venue for countless mass rallies over almost five decades by the Communist government led until 2006 by Fidel Castro.

The altar was placed at the foot of the towering Jose Marti monument, which honours Cuba's most important independence-era hero.

Among the popular preparations – workers paved the heavily used Rancho Boyeros Avenue that leads to Jose Marti International Airport, and other streets on which the bullet-proof, pearly white Popemobile will roll by.

But in contrast to John Paul II's visit, Havana has not been supplied with much in the way of commemorative trinkets like T-shirts, pens or busts of the pontiff.

On Sunday in Mexico, Benedict XVI sought to boost the Catholic faith in the face of violence and other challenges.

"There is no reason ... to give in to the despotism of evil. Let us instead ask the risen Lord to manifest his power," he said before Latin American bishops in the cathedral of Leon.

At a vast open-air mass, the pope also referred to Christ the King, whose statue, also a major Mexican icon, towered over Bicentennial Park where the event took place.

"His kingdom does not stand on the power of his armies subduing others through force or violence. It rests on a higher power than wins over hearts: the love of God," the pope said before an estimated crowd of more than half a million gathered in the blazing sun in the highly Catholic state of Guanajuato.

The mass was a highlight on the 84-year-old pope's last day in Mexico, on a visit which began in the shadow of his charismatic predecessor John Paul II, who made the trip five times, but ended up drawing a swell of popular support.